You’d think vitamin deficiencies would be rare in the United States, but many people are running low on vitamin D, and it’s a serious health threat.
Being short on vitamin D not only affects bone density, it’s also been linked to conditions such as heart disease, mental decline, some types of cancer, autoimmune diseases, infectious diseases and type 2 diabetes.
The problem is twofold: Not knowing how much vitamin D you really need, and how to get it. While 600 to 800 International Units (IUs) is the recommended daily amount, it can take more than that to bring you up to a healthy level and maintain it once you have a deficit.